Modern vehicles use a variety of structures to protect the vehicle's occupants during a crash. Some of these structures are used to control the transmission of the crash energy to the passenger compartment while other structures, such as seat belts, head restraints, and air bags, are intended to restrain passenger movement during a crash, thereby preventing the passengers from hurting themselves as their bodies react to the crash forces. In addition to reducing the potential for personal injuries, many vehicle crash structures are also designed to minimize vehicle damage and simplify post-crash repairs.
A variety of different approaches and structures have been used to absorb and control the transmission of crash energy into the vehicle. As the bumper is typically the first vehicle structure to be impacted during a crash, many crash structures attempt to absorb as much energy as possible in the bumper itself, thus minimizing the energy that is transmitted into the vehicle. For example, U.S. Pat. No. 4,018,466 discloses a bumper assembly in which the bumper is comprised of a hollow beam that houses a plurality of shock absorbing cellular blocks. The shock absorbing cellular blocks are inserted into pocket-like sections of the bumper. In an alternate shock-absorbing bumper, disclosed in U.S. Pat. No. 6,000,738, the bumper includes an outer wall disposed to receive the crash force, an inner wall that is coupled to the vehicle structure and four walls that connect the inner and outer bumper walls. During a car crash, the four connecting walls are designed to bend at a controlled rate, thereby absorbing crash energy.
While crash energy may be absorbed in the bumper, large impact crashes typically require the use of other energy absorbing structures. For example, in a conventional vehicle the bumpers are often coupled to the vehicle by one or more crash boxes that are designed to collapse during a crash, thereby absorbing crash energy. U.S. Pat. No. 7,290,811 discloses one design for a crash box in which two overlapping and interconnected sheet metal shells form the crash box. The crash box is bolted to the bumper cross-member using at least one bolt that extends in a vertical direction through the overlap zone of the structure. U.S. Pat. No. 7,533,913 discloses an alternate crash box design using inner and outer curved members which extend in the longitudinal direction of the vehicle. The inner member includes a plurality of bead-shaped protrusions that are intended to cause longitudinal compressing deformation of this member in a low-speed collision, thereby helping to direct the striking energy created by the collision away from the inside of the vehicle.
In addition to designing the front structure of a vehicle to absorb and distribute the impact loads generated during a crash, it is critical that these same structures also achieve the desired level of vehicle stability and maneuverability, preferably in a lightweight structure that minimizes its impact on the vehicle's MPG or MPGequivalent. One attempt at balancing these goals is disclosed in U.S. Patent Application Publication No. 2004/0056515, published 25 Mar. 2004, in which a relatively simple front structure is provided that is designed to be rigid and, due to the elimination of various reinforcing members, lightweight.
It is therefore an object of the present invention to provide a vehicle front structure that achieves improved performance in terms of front impact load distribution, structure weight, vehicle frame rigidity, and vehicle maneuverability.